Comparison Between RCCE and Shock Tube Ignition Delay Times at Low Temperatures

2015 ◽  
Vol 137 (6) ◽  
Author(s):  
Ghassan Nicolas ◽  
Hameed Metghalchi
Keyword(s):  
Free Energy ◽  
Shock Tube ◽  
Ignition Delay ◽  
Low Temperatures ◽  
Reduction Technique ◽  
Experimental Measurements ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Constrained Equilibrium ◽  
Rate Controlled

The rate-controlled constrained-equilibrium (RCCE) method is a reduction technique based on local maximization of entropy or minimization of a relevant free energy at any time during the nonequilibrium evolution of the system subject to a set of kinetic constraints. In this paper, RCCE has been used to predict ignition delay times of low temperatures methane/air mixtures in shock tube. A new thermodynamic model along with RCCE kinetics has been developed to model thermodynamic states of the mixture in the shock tube. Results are in excellent agreement with experimental measurements.

Methanol Oxidation Induction Times Using the Rate-Controlled Constrained-Equilibrium Method

2003 ◽  
Author(s):  
Sergio Ugarte ◽  
Mohamad Metghalchi ◽  
James C. Keck
Keyword(s):  
Methanol Oxidation ◽  
Ignition Delay ◽  
Rate Equations ◽  
Oxygen Mixture ◽  
Free Oxygen ◽  
Equilibrium Method ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Constrained Equilibrium ◽  
Rate Controlled

Methanol oxidation has been modeled using the Rate-Controlled Constrained-Equilibrium method (RCCE). In this method, composition of the system is determined by constraints rather than by species. Since the number of constraints can be much smaller than the number of species present, the number of rate equations required to describe the time evolution of the system can be considerably reduced. In the present paper, C1 chemistry with 29 species and 140 reactions has been used to investigate the oxidation of stoichiometric methanol/oxygen mixture at constant energy and volume. Three fixed elemental constraints: elemental carbon, elemental oxygen and elemental hydrogen and from one to nine variable constraints: moles of fuel, total number of moles, moles of free oxygen, moles of free oxygen, moles of free valence, moles of fuel radical, moles of formaldehyde H2CO, moles of HCO, moles of CO and moles of CH3O were used. The four to twelve rate equations for the constraint potentials (LaGrange multipliers conjugate to the constraints) were integrated for a wide range of initial temperatures and pressures. As expected, the RCCE calculations gave correct equilibrium values in all cases. Only 8 constraints were required to give reasonable agreement with detailed calculations. Results of using 9 constraints showed compared very well to those of the detailed calculations at all conditions. For this system, ignition delay times and major species concentrations were within 0.5% to 5% of the values given by detailed calculations. Adding up to 12 constraints improved the accuracy of the minor species mole fractions at early times, but only had a little effect on the ignition delay times. RCCE calculations reduced the time required for input and output of data in 25% and 10% when using 8 and 9 constraints respectively. In addition, RCCE calculations gave valuable insight into the important reaction paths and rate-limiting reactions involved in methanol oxidation.

Application of an aerosol shock tube to the measurement of diesel ignition delay times

2009 ◽  
Vol 32 (1) ◽  
pp. 477-484 ◽  
Author(s):  
D.R. Haylett ◽  
P.P. Lappas ◽  
D.F. Davidson ◽  
R.K. Hanson
Keyword(s):  
Shock Tube ◽  
Ignition Delay ◽  
Ignition Delay Times ◽  
Delay Times

scholarly journals Shock tube ignition delay times and methane time-histories measurements during excess CO2 diluted oxy-methane combustion

2016 ◽  
Vol 164 ◽  
pp. 152-163 ◽  
Author(s):  
Batikan Koroglu ◽  
Owen M. Pryor ◽  
Joseph Lopez ◽  
Leigh Nash ◽  
Subith S. Vasu
Keyword(s):  
Shock Tube ◽  
Ignition Delay ◽  
Methane Combustion ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Time Histories

Ignition delay times of methane fuels at thrust chamber conditions in an ultra-high-pressure shock tube

2022 ◽  
Author(s):  
Michael Pierro ◽  
Andrew Laich ◽  
Justin J. Urso ◽  
Cory Kinney ◽  
Subith Vasu ◽  
...  
Keyword(s):  
High Pressure ◽  
Shock Tube ◽  
Ignition Delay ◽  
Pressure Shock ◽  
Thrust Chamber ◽  
Ultra High Pressure ◽  
Ignition Delay Times ◽  
Delay Times

scholarly journals Aerosol Shock Tube Designed for Ignition Delay Time Measurements of Low-Vapor-Pressure Fuels and Auto-Ignition Flow-Field Visualization

Energies ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 683
Author(s):  
Erwei Liu ◽  
Qin Liao ◽  
Shengli Xu
Keyword(s):  
Flow Field ◽  
Vapor Pressure ◽  
Shock Tube ◽  
Ignition Delay ◽  
Pressure Sensors ◽  
Local Pressure ◽  
Ignition Delay Times ◽  
Auto Ignition ◽  
Delay Times ◽  
Sequential Images

An aerosol shock tube has been developed for measuring the ignition delay times (tig) of aerosol mixtures of low-vapor-pressure fuels and for visualization of the auto-ignition flow-field. The aerosol mixture was formed in a premixing tank through an atomizing nozzle. Condensation and adsorption of suspended droplets were not observed significantly in the premixing tank and test section. A particle size analyzer was used to measure the Sauter mean diameter (SMD) of the aerosol droplets. Three pressure sensors and a photomultiplier were used to detect local pressure and OH emission respectively. Intensified charge-coupled device cameras were used to capture sequential images of the auto-ignition flow-field. The results indicated that stable and uniform aerosol could be obtained by this kind of atomizing method and gas distribution system. The averaged SMD for droplets of toluene ranged from 2 to 5 μ m at pressures of 0.14–0.19 MPa of dilute gases. In the case of a stoichiometric mixture of toluene/O2/N2, ignition delay times ranged from 77 to 1330 μs at pressures of 0.1–0.3 MPa, temperatures of 1432–1716 K and equivalence ratios of 0.5–1.5. The logarithm of ignition delay times was approximately linearly correlated to 1000/T. In contrast to the reference data, ignition delay times of aerosol toluene/O2/N2 were generally larger. Sequential images of auto-ignition flow-field showed the features of flame from generation to propagation.

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